Fluid motor and control valve assembly therefor



Nov. 19, 1968 BENJAMIN ETAL 3,411,415

FLUID MOTOR AND CONTROL VALVE ASSEMBLY THEREFOR Filed March 14, 1966 u T L 1 6 M l2 KR 1a S so 5 8 L 6| 35 4O 9 4 M 60 8 49 42 47 4 2o -|3 l0 1 50 57 74 52 5s 48 f|4 55 5 46 l 28 3 2\3 2 1 \wl INVENTORS 15. 5 MILTON 1.. BENJAMIN DAV/0 D. WALKER BY W,M 4a0mmw! ATTORNEYS United States Patent 015cc 3,4 1 1,415 Patented Nov. 1 9, 1 968 3,411,415 FLUID MOTOR AND CONTROL VALVE ASSEMBLY THEREFOR Milton L. Benjamin and David D. Walker, Chagrin Falls,

Ohio, assignors to Erickson Tool Company, Solon, Ohio,

a corporation of Ohio Filed Mar. 14, 1966, Ser. No. 534,140 9 Claims. (Cl. 91420) ABSTRACT OF THE DISCLOSURE A fluid motor and control valve assembly including a pair of check valve means for permitting flow into opposite ends of said motor and a pair of plunger means associated with said check valve means movable into engagement with the check valve means associated with the end of the motor which is to be vented when high fluid pressure is being admitted to the other end of the motor to unseat the same.

Disclosure This invention relates generally, as indicated, to a fluid motor and control valve assembly therefor and, more particularly, to a novel fluid motor and control valve assembly which may be used to hold a chuck or the like in any selected position despite a loss of fluid actuating pressure, unaffected by centrifugal force even at high operating speeds.

While control valve assemblies for trapping the operating fluid in a motor to hold a chuck in chucking position even when there is a loss of fluid pressure for actuating the chuck are not new, such devices presently available are generally only efiective to trap the fluid when the chuck is stationary or rotating at relatively slow speeds, since the centrifugal force which is developed at high operating speeds usually causes a slight shifting of the movable parts of the control valve assembly to positions whereat there is leakage of the trapped fluid.

It is accordingly a primary object of this invention to provide a fluid motor and novel control valve assembly therefor of the type indicated, but which is unaffected by centrifugal force regardless of the rotational speed thereof, whereby the actuating fluid may be turned off once the motor has been actuated to the desired position to allow for high speed rotation without overheating of the rotary coupling and consequent damage to the rotary coupling seals.

Another object is to provide such a fluid motor and control valve assembly therefor in which the poppets of the control valve assembly are located on center with respect to the axis of rotation of the motor to completely nullify the effect of centrifugal force acting thereon and permit high speed rotation without any loss of trapped motor fluid.

Still another object is to provide such a fluid motor and control valve assembly therefor with a novel check valve arrangement which traps fluid in the motor cylinder tending to move the motor piston in one direction so long as there is little or no fluid pressure tending to move the piston in the opposite direction unaffected by centrifugal force, and which permits the trapped fluid to escape when the fluid pressure tending to move the piston in the opposite direction is high.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed.

In such annexed drawing:

FIG. 1 is a longitudinal cross-section view of a preferred embodiment of'fiuid motor and control valve assembly therefor in accordance with this invention connected to a chuck or the like with the jaws of the chuck in workpiece releasing position; and

FIG. 2 is a longitudinal cross-section view similar to FIG. 1, but with the jaws of the chuck in workpiece gripping position.

Turning now to the details of the preferred form of fluid motor and control valve assembly 1 illustrated by way of example in the drawing, such fluid motor and con- 'trol' valve assembly generally comprises a two-part housing 2 in which the housing part 3 has a recess 4 and the housing part 5 is secured to the housing part 3 as by means of suitable fasteners 6 to define therebetween a fluid cylinder 7 with a piston 8 slidably received therein. The piston rod 9 is shown connected to the jaws 10 of a chuck 11 of conventional type for actuation of the jaws 10 into and out of workpiece gripping position upon axial movement of the piston rod 9 in opposite directions, in a manner which will be fully explained hereinbelow. However, it should be understood that the fluid motor and control valve assembly 1 could be used to operate many devices other than chucks.

The body 12 of the chuck 11 has a plurality of radial slots 13 in the front face 14 for receipt of the jaws 10. Contained in recesses in the body 12 are a plurality of operating levers 15, one for each jaw 10, mounted on trunnions 16 for pivotal movement. The operating levers each have a generally axially outwardly extending arm 17 which is received in a slot 18 in the associated jaw mounting 19, and a generally radially inwardly extending arm 20 projecting into a tapered annular groove 21 of an axially movable slider element 22 connected to the piston rod 9 by means of a draw rod 23. The spindle S which supports the chuck body 12 is attached to the fluid motor housing 2 by a suitable coupling 24 and is adapted to be driven by a machine tool, not shown, in conventional manner.

As evident, when the piston rod 9 is moved toward the right as viewed in FIG. 1 to cause a corresponding movement of the slider element 22, the shoulder 25 of the tapered groove 21 engages the lever arms 20 to cause them to rotate in a direction for moving the jaws 10 radially out of gripping engagement with a workpiece disposed therebetween. Conversely, when the piston rod 9 is moved in the reverse direction toward the left to the FIG. 2 position, the tapered surface of the groove 21 engages the lever arms 20 to cause them to rotate in a direction moving the jaws 10 radially inwardly into workpiece gripping engagement.

For supplying a suitable compressible fluid such as ail to the motor 1, there is a rotary coupling 28 mounted or the motor housing 2 which has a pair of ports 29 and 3( through which the air is selectively admitted under pres sure to the fluid cylinder 7 to move the piston 8 in oppo site directions with the motor housing 2 and spindle E rotating and the rotary coupling 28 stationary, as wel known in the art. One of the ports 29 is in fluid com munication with the near end of the cylinder 7 via pas sage and recess 36 in the housing part 5 with th: longitudinal axis of the recess 36 being in line with tilt axis of rotation of the housing 2. The other port 30, or the other hand, is in fluid communication with the fa' end of the fluid cylinder 7 through communicating pas sages 37 and 38 in the housing parts 5 and 3, respectively an annular groove 39 in the wall of the opening 40 through which the piston rod 9 extends from the housing 2, a first passage 41 in the piston rod 9 extending between the annular groove 39 and a recess 42 in the piston 8 in line with the recess 36 in the housing part 5, and a second passage 44 in such iston 8 communicating the recess 42 with the interior of the cylinder 7 adjacent the far side of the piston 8. concentrically located within the recesses 36 and 42 are one-way check-valve assemblies 45 and 46, each consisting of a sleeve member 47 having a seat 48 therein and a poppet valve 49 which is yieldably held in engagement with the seat 48 by a spring 50 for permitting flow of fluid under pressure from the associated ports 29 and 30 into the respective ends of the fluid cylinder 7, but not in the reverse direction. There is also provided a plunger 52 in each check valve assembly 45 and 46 having an effective area greater than the effective area of the associated poppet valve 49 with an extension 53 projecting toward the poppet 49, whereby high-fluid pressure in the port 29 which enters the head end of the fluid cylinder 7 will act on the plunger 52 of the check valve assembly 46 to cause the same to open the associated poppet valve 49 for exhaust of fluid from the rod end of the cylinder 7, and high-fluid pressure in the port 30 acting on the plunger 52 of the check valve assembly 45 via a branch passage 55 will cause opening of its associated poppet 49 for exhaust of fluid from the head end of such cylinder. Any suitable means such as the retainer plate 56 or snap ring 57 may be used to hold the check valve assemblies 45 and 46 in place.

In operation, when it is desired to actuate the fluid motor and control valve assembly 1 to move the chuck 11 or other such device to workpiece gripping position, air under pressure from a suitable source, not shown, is admitted to the rod end of the cylinder 7 through the port 30 and check valve assembly 46 as indicated by the arrows in FIG. 2 to move the piston 8 to the FIG. 2 position. At the same time, the high pressure entering the rod end of the cylinder 7 also acts on the plunger 52 of the check valve assembly 45 via passage 37 and branch passage 55 to open its associated poppet 49 for permitting the escape of fluid from the head end of the cylinder 7 through the check valve assembly 45, passage 35, and port 29.

As evident, the air entering the rod end of the cylinder 7 will not be permitted to escape through the check valve assembly 46 unless and until high fluid pressure is admitted to the head end of such cylinder to cause the plunger 52 of the check valve assembly 46 to move to a position unseating the associated poppet valve 49. Accordingly, once the chuck jaws 10 are brought into tight gripping engagement with a workpiece, they will be maintained in such position as long as desired even though there may be some fluid leakage from the system upstream of the cylinder 7 or even a complete loss of fluid pressure at the inlet port 30. This is true regardless of the speed at which the fluid motor 1 and chuck 11 are being rotated, since the centrifugal force acting on the check valve assemblies 45 and 46 will not aflect the position of the poppet valves 49 due to the location of such poppets on center with the axis of rotation of the motor 1. Accordingly, once the chuck 11 is actuated to a selected position, the air may be turned off to prevent overheating of the rotary coupling 28 and consequent damage to the coupling seals 60 and 61 without loss of any trapped motor fluid even at high speed rotation.

Release of the trapped air and thus release of the chuck jaws 10 from a workpiece can only be effected by supplying air under pressure through the port 29 to the head end of the cylinder 7 via the passage 35, recess 36 and check valve assembly 45. As discussed above, this high-fluid pressure entering the fluid cylinder 7 through the check valve assembly 45 acts on the plunger 52 of the other check valve assembly 46 to move it to a position unseating the associated poppet valve 49, whereby the trapped air at the other end of the cylinder is permitted to escape through the check valve assembly 46 via passages 44, 41, recess 42, passages 38, 37, and port 30.

It can now be seen that the hydraulic motor and control valve assembly therefor of the present invention is of a unique construction which permits turning off of the fluid actuating pressure after the motor piston has been moved to any desired position to preclude overheating of the rotary coupling and damage to the seals thereof during high speed rotation without fear of losing any of the trapped fluid for maintaining the motor in such position.

Other modes of applying the principles of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We therefore, particularly point out and distinctly claim as our invention:

1. In combination, a fluid motor and control valve assembly comprising a housing having a motor cylinder therein, a piston slidably received in said cylinder, passages in said housing for selectively communicating opposite ends of said cylinder with a fluid pressure source, and first and second valve means in said passages for trapping fluid in opposite ends of said cylinder to maintain said piston in a selected position despite subsequent loss in fluid pressure upstream of said cylinder, the longitudinal axes of said first and second valve means being in line with the longitudinal axis of said motor, whereby rotation of said motor about its longitudinal axis will not create a centrifugal force tending to shift said valve means to ta position permitting leakage of such trapped fluid, and means for permitting the trapped fluid to escape from one end of said cylinder in response to high fluid pressure being admitted to the other end of said cylinder and vice versa, one of said valve means being concentrically mounted in said piston for movement therewith, said piston having a rod extending through an opening in said housing, and a further passage in said rod which communicates the rod side of said piston with one of said passages in said housing in selective communication with such fluid pressure source, said one valve means being mounted in said further passage coaxially with said piston.

2. A fluid motor and control valve assembly comprising a housing having a motor cylinder therein, a piston slidably received in said cylinder, passages in said housing for selectively communicating opposite ends of said cylinder with a fluid pressure source, a first check valve means in one of said passages for permitting fluid flow into one end of said cylinder and trapping such fluid in said one end to maintain said piston in a selected position despite subsequent loss in fluid pressure upstream of said cylinder, a first axially movable plunger means mounted for movement into engagement with said first check valve means to unseat the same and thereby permit the escape of fluid from said one end of said cylinder in response to high fluid pressure being admitted into the other end of said cylinder, a second check valve means in another of said passages for permitting flow of fluid into the other end of said cylinder and trapping suoh fluid in said other end to maintain said piston in another selected position despite subsequent loss of fluid pressure upstream of said cylinder, and a second axially movable plunger means mounted for movement into engagement with said second check valve means to permit the trapped fluid to escape from said other end of said cylinder in response to high fluid pressure being admitted to said one end of said cylinder, one of said cylinder, one of said check valve means and plunger means being mounted in said piston for movement therewith, said one plunger means being directly exposed to fluid pressure in an end of said cylinder for direct actuation thereby as foresaid, said piston having a rod extending through an opening in said housing, and a further passage in said rod which communicates the rod side of said piston with one of said passages in said housing in selective communication with such fluid pressure source, said one check valve means being mounted in said further passage coaxially with said piston.

3. The fluid motor and control valve assembly of claim 2 further comprising a rotary coupling connected to said motor through which opposite ends of said cylinder are selectively communicated with such fluid pressure source as aforesaid, said check valve means permitting turning off of such fluid pressure upstream of said rotary coupling to prevent overheating of said coupling and consequent damage of the coupling seals without loss of such trapped fluid in said cylinder.

4. In combination, a fluid motor and control valve assembly comprising a housing having a motor cylinder therein, a piston slidably received in said cylinder, passages in said housing -for selectively communicating opposite ends of said cylinder with a fluid pressure source, and first and second valve mean in said passages for trapping fluid in opposite ends of said cylinder to maintain said piston in a selected position despite subsequent loss in fluid pressure upstream of said cylinder, the longitudinal axes of said first and second valve means being in line with the longitudinal axis of said motor, whereby rotation of said motor about its longitudinal axis will not create a centrifugal force tending to shift said valve means to a position permitting leakage of such trapped fluid, and means for permitting the trapped fluid, and means for permitting the trapped fluid to escape from one end of said cylinder in response to high fluid pressure being admitted to the other end of said cylinder and vice versa, one of said valve means being concentrically mounted in said piston for movement therewith, said piston having a rod extending through an opening in said housing, and a further passage in said rod and piston which communicates the rod side of said piston with one of said passages in said housing in selective communication with such fluid pressure source, said one valve means being mounted in said fiurther passage coaxial with said piston.

5. The combination of claim 4 wherein the means for permitting trapped fluid to escape from the rod end of said cylinder comprises a plunger disposed in a central recess in said piston and exposed to fluid pressure in the head end of said cylinder, said plunger having an extension projecting toward said one valve means for engagement therewith to open said one valve means and thus permit the escape of trapped fluid from said rod end of said cylinder in response to high fluid pressure entering said head end of said cylinder.

6. The combination of claim 5 wherein the means for permitting trapped fluid to escape from the head end of said cylinder comprises another plunger disposed in a central recess in the head of said cylinder exposed to fluid pressure in the passage leading to the rod end of said cylinder, said another plunger having an extension projecting toward the other valve means for movement into engagement therewith to open said other valve means and thus permit the escape of trapped fluid from the head end of said cylinder in response to high fluid pressure entering the rod end of said cylinder.

7. A fluid motor and control valve assembly com prising a housing having a motor cylinder therein, a piston slidably received in said cylinder, passages in said housing for selectively communicating opposite ends of said cylinder with a fluid pressure source, a first check valve means in one of said passages for permitting fluid flow into one end of said cylinder and trapping suci fluid in said one end to maintain said piston in a selecte position despite subsequent loss in fluid pressure upstrear of said cylinder, a first axially movable plunger mean mounted for movement into engagement with said firs check valve means to unseat the same and thereby pei mit the escape of fluid from said one end of said cylinde in response to high fluid pressure being admitted int the other end of said cylinder, a second check valv means in another of said passages for permitting fiOl of fluid into the other end of said cylinder and trappin such fluid in said other end to maintain said piston i anot'her selected position despite subsequent loss of flui pressure upstream of said cylinder, and a second axiall movable plunger means mounted for movement int engagement with said second check valve means to per mit the trapped fluid to escape from said other end c said cylinder in response to high fluid pressure bein admitted to said one end of said cylinder, one of said ohec valve means and plunger means being mounted in sai piston for movement therewith, said one plunger mean being directly exposed to fluid pressure in an end c said cylinder for direct actuation thereby as aforesaic said piston having a rod extending through an openin in said housing, and a further passage in said rod an piston which communicates the rod side of said pisto with one of said passages in said housing in selectiv communication with such fluid pressure source, said on check valve means being mounted in said further passag coaxially with said piston.

8. The fluid motor and control valve assembly c claim 7 wherein said one plunger means is disposed i a central recess in said piston and exposed to fluid pres sure in the head end of said cylinder, said one plunge means having an extension projecting towards said on check valve means for engagement therewith to ope said one check valve means and thus permit the escap of trapped fluid from said rod end of said cylinder i response to high fluid pressure entering said head end c said cylinder.

9. The fluid motor and control valve assembly of clail 7 wherein the other plunger means is disposed in a centrz recess in the head end of said cylinder exposed to flui pressure in the passage leading to the rod end of sai cylinder, said other plunger means having an extensio projecting toward said other check valve means for movr ment into engagement therewith to open said other chec valve means and thus permit the escape of trapped flui from the head end of said cylinder in response to big fluid pressure entering the rod end of said cylinder.

References Cited UNITED STATES PATENTS 2,809,612 10/ 1957 Highberg 279- 3,273,467 9/1966 Allen 9142 3,274,902 9/1966 Kleckner 91-42 FOREIGN PATENTS 175,678 6/ 1961 Sweden. 893,678 4/ 1962 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

B. L. ADAMS, Assistant Examiner. 

